The invention relates to a novel separating material for chromatography which essentially comprises a support and cyclodextrin chemically bonded thereto via a carbamic acid group, to the production thereof, and to the use thereof for improved separation of mixtures of substances and enantiomers by chromatography.
The use of cyclodextrins in the chromatographic separation and purification processes is described, for example, in a review by W.L. Hinze, Separation and Purification Methods, 10 (2) 159-237 (1981). However, when cyclodextrin solutions are used as the mobile phase, considerable problems are caused by the inadequate solubility of the 8-cyclodextrins. Cyclodextrin has been experimentally tested as the stationary phase. To this end, polymeric materials were prepared. However, these polymeric gels require a long analysis time and also exhibit low mechanical stability, meaning that these materials are not suitable for high-performance liquid chromatography (HPLC).
Attempts have therefore been made to bond cyclodextrins to a solid matrix. Cyclodextrins are known which are bonded to silica gel via amine or amide bonds. However, these bonds were hydrolytically unstable. It was therefore not possible to work in the aqueous phase. U.S. Pat. No. 4,539,399 describes cyclodextrins coupled to silica gel via a bond without nitrogen. The bond between cyclodextrin and the support generally takes place here via an ether bridge. However, the disadvantage of these materials is that a large number of enantiomeric mixtures, for example pharmaceutical active ingredients or sugar-like derivatives, cannot be separated using these materials.